CN116351351A

CN116351351A - Transistor optical tweezers with increased illuminated intensity and microfluidic device

Info

Publication number: CN116351351A
Application number: CN202111625050.5A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Caike Suzhou Biotechnology Co ltd
Current assignee: Caike Suzhou Biotechnology Co ltd
Priority date: 2021-12-28
Filing date: 2021-12-28
Publication date: 2023-06-30
Also published as: WO2023125488A2; WO2023125488A3

Abstract

The invention provides a transistor optical tweezer, comprising: a first electrode; a second electrode; an array of phototransistors disposed between the first electrode and the second electrode, each phototransistor being physically isolated from each other by a first insulating element, each phototransistor including a collector region, a base region, and an emitter region supported by a substrate; the emitter region of each phototransistor includes at least two sub-emitter regions, each sub-emitter region being physically separated at least in part by the base region, and the at least two sub-emitter regions having a common base region and collector region. The transistor structure achieves a larger photo-generated current without changing the intensity of the illuminating beam or the window size of the transistor, thereby enabling a larger DEP force to be generated. In addition, the presence of multiple sub-emissive regions results in a denser, more uniform distribution of the non-uniform electric field generated by the illumination relative to the undivided emissive regions, thereby facilitating manipulation of the micro-object.

Description

Transistor optical tweezers with increased illuminated intensity and microfluidic device

Technical Field

The present invention relates to an optical tweezer device for phototransistor-based, in particular to a transistor optical tweezer device with increased illuminated intensity and a microfluidic device comprising the transistor optical tweezer device.

Background

Transistor-based optical tweezers technology has been applied to manipulation (e.g., selection or movement) of micro-objects such as cells, microspheres, etc. A typical construction of this type of optical tweezer device is to provide a microfluidic channel between an upper electrode, typically a glass plate coated with Indium Tin Oxide (ITO), and a lower electrode, typically a metal electrode, on which an array of phototransistors is provided in place of a conventional phototransistor. When patterned light impinges on a particular area on the phototransistor array, the activated transistors allow current to pass, thereby creating a non-uniform electric field across the microfluidic channel, creating Dielectrophoretic (DEP) forces that can manipulate the micro-object.

The amount of DEP force is dependent on factors such as the volume of the controlled micro-object and the medium in which it is located. For a given substance to be tested, the illuminated intensity and/or illuminated area of the phototransistor is increased, so that a larger photogenerated current can be obtained, thereby facilitating the establishment of a more pronounced nonuniform electric field, and thereby generating a larger DEP manipulation force.

CN 107223074B discloses a transistor optical tweezers and a microfluidic device thereof, each transistor structure comprising a lateral transistor and a longitudinal transistor, in each transistor structure a P-type base region surrounding an N-type emitter region, an N-type collector region surrounding a P-type base region, and both the base region and the collector region comprising a lateral portion and a longitudinal portion, the lateral and longitudinal currents being generated simultaneously at the same light intensity compared to an optical tweezers with only a longitudinal transistor, the additional lateral transistor purportedly increasing the intensity of the generated current, allowing a more robust control of the micro-object.

However, the manufacturing process of such a transistor structure is complex, and particularly, the control of the lateral portions of the base region and the collector region needs to be very precise, which may easily cause that the lateral current cannot be normally generated, and even the entire transistor cannot be normally operated.

In view of the foregoing, there is a need in the art for an improved optical tweezers device and corresponding microfluidic device that overcomes the above-described drawbacks of the prior art.

Disclosure of Invention

One aspect of the present invention provides a transistor optical tweezer comprising: a first electrode; a second electrode electrically connectable to the first electrode; a phototransistor array disposed between the first electrode and the second electrode, the phototransistor array being comprised of phototransistors distributed in an array, each phototransistor being physically separated from each other by a first insulating element, each phototransistor including a collector region, a base region, and an emitter region supported by a substrate; a microfluidic channel disposed between the first electrode and the array of phototransistors, wherein for each phototransistor its emitter region comprises at least two sub-emitter regions that are physically separated at least in part by the base region, and the at least two sub-emitter regions have a common base region and collector region.

In some embodiments, the base region includes a lateral portion extending to the first insulating element and a longitudinal portion extending from the lateral portion, the longitudinal portion including a first longitudinal portion extending from the lateral portion of the base region to the second insulating element and physically isolating at least in part the sub-emitter. In some embodiments, at least one sub-emitter is physically separated by a lateral portion of the base region, a first longitudinal portion of the base region, and the first insulating element.

In some embodiments, the longitudinal portion includes a second longitudinal portion abutting and extending along at least one of the first insulating elements, the second longitudinal portion being spaced apart from the first longitudinal portion. In some embodiments, the at least one sub-emitter is physically separated by a lateral portion of the base region, a first longitudinal portion of the base region, and a second longitudinal portion of the base region.

In some embodiments, the first longitudinal portion comprises a plurality of first longitudinal portions that are parallel and/or perpendicular to each other. In some embodiments, the at least one sub-emitter is physically isolated only by the lateral portion of the base region and the first longitudinal portion of the base region.

In some embodiments, each sub-emitter is surrounded by a base region but at least partially exposed to the microfluidic channel.

In some embodiments, the first longitudinal portion has a first width and the second longitudinal portion has a second width, the first width and the second width independently being about 100 nm to about 1,000 nm. In some embodiments, the width of each of the first longitudinal portions is independently from about 100 nm to about 1,000 nm.

In some embodiments, each sub-emitter comprises a first doped region and a second doped region, the first doped region having a higher doping concentration than the second doped region. In some embodiments, the first doped region has a doping concentration of about 10 ¹⁸ cm ^-3 To about 10 ²¹ cm ^-3 The second doped region has a doping concentration of about 10 ¹⁵ cm ^-3 To about 10 ¹⁸ cm ^-3 。

In some embodiments, the emitter region of each phototransistor includes three, four, six, eight, or nine sub-emitter regions. In some embodiments, the emitter region of each phototransistor includes four sub-emitter regions. In some embodiments, each of the sub-emissive areas has a substantially equal volume. In some embodiments, each sub-emissive region has a volume that is not substantially equal.

In some embodiments, the collector region of each phototransistor extends laterally to the first insulating element and does not have a longitudinal extension.

In some embodiments, each phototransistor is spaced apart at a pitch of about 5 microns to about 20 microns. In some embodiments, all sub-emitter regions of each phototransistor are separated by the spacing in an equal or unequal manner.

In some embodiments, the first electrode is a glass plate coated with a conductive film. In some embodiments, the conductive film is an indium tin oxide film. In some embodiments, the second electrode is a metal electrode. In some embodiments, the metal electrode is a gold electrode.

In some embodiments, the microfluidic channel comprises a conductive medium having cells. In some embodiments, the conductivity of the conductive medium is from about 1 to about 10 mS/cm. In some embodiments, the conductive medium is a cell culture solution or a physiological solution. In some embodiments, the cell culture fluid or physiological solution comprises cells. In some embodiments, the cell is a hybridoma cell.

Another aspect of the invention provides a microfluidic device comprising any of the transistor optical tweezers of the present invention. In some embodiments, the microfluidic device further comprises a control system, a light pattern generation system, and an image acquisition system.

By providing a longitudinal extension of the base region, on the one hand, the presence of the longitudinal extension brings the base region closer to the light beam, and thus the illuminated intensity of the base region is greater, and at the same illumination intensity, the base region of the invention is able to receive more photons than a base region without a longitudinal portion. On the other hand, the light transmittance of the insulating coating is generally better than that of the emitter region overlying the base region, and the longitudinal portion is therefore able to receive more photons. Therefore, the transistor structure realizes larger photo-generated current without changing the light intensity of the irradiation light beam or the window size of the transistor, thereby generating larger DEP force and facilitating the manipulation of micro-objects in the micro-fluid channel. In addition, the presence of multiple sub-emissive regions results in a denser, more uniform distribution of the non-uniform electric field generated by the illumination relative to the undivided emissive regions, thereby facilitating manipulation of the micro-object.

Drawings

The invention will be described in more detail with reference to the accompanying drawings. It is noted that the illustrated embodiments are merely representative examples of the embodiments of the present invention, and that elements in the drawings are not drawn to scale such as actual dimensions, the number of actual elements may vary, the relative positional relationship of the actual elements is substantially consistent with the illustration, and some elements are not shown in order to more clearly illustrate the details of the exemplary embodiments. Where multiple embodiments exist, while one or more features described in the previous embodiments may also be applied to another embodiment, for brevity, the latter embodiment or embodiments will not be described in further detail as having described such features, unless otherwise indicated. Those skilled in the art will appreciate upon reading the present disclosure that one or more features illustrated in one drawing may be combined with one or more features in another drawing to construct one or more alternative embodiments not specifically illustrated in the drawings, which also form a part of the present disclosure.

Fig. 1A shows a partial cross-sectional view of an optical tweezer device according to an embodiment of the present invention.

Fig. 1B shows a partial top view of the optical tweezer device of fig. 1A.

Fig. 1C shows a partial perspective view of the transistor array.

Fig. 1D shows a schematic diagram of a microfluidic device comprising the optical tweezers device.

Figure 2A shows a partial cross-sectional view of a transistor array of an optical tweezer device according to another embodiment of the present invention.

Fig. 2B shows a partial top view of the transistor array shown in fig. 2A.

Fig. 3 shows a partial cross-sectional view of a transistor array of an optical tweezer device according to another embodiment of the present invention.

Fig. 4 shows a partial cross-sectional view of a transistor array of an optical tweezer device according to another embodiment of the present invention.

Fig. 5 shows a flow chart of a method of manufacturing a transistor array according to an embodiment of the invention.

The meaning of the reference numerals is summarized as follows. Like reference numerals denote like elements, and a repeated arrangement of like elements is denoted by letters after the numerals when applicable. For example, reference numerals 108a, 108b, 108c, and 108d represent four repetitions of element 108. 102. 202, 302, 402-a first doped region; 104. 204, 304, 404-a second doped region; 105. 205, 305-emitter region; 106. 206, 306, 406-base region; 108. 208, 308, 408-collector regions; 110. 210, 310, 410-substrate; 112. 212, 312, 412-insulating cover layers; 114-conductive plating; 116-a second electrode; 118-cells; 120. 220, 320, 420-a first insulating element; 122-microfluidic channel; 124-a first electrode; 126-phototransistors; 128-a first electrode plate; 140. 240, 340, 440-a second insulating element; 142. 242, 342, 442-first longitudinal portion; 144. 146, 244, 246-a second longitudinal portion; 150. 250, 350, 450-transverse portions; 148. 248, 348, 448-insulating barriers; 130-light pattern generating means; 132-an image acquisition device; 134-computer system; 136-a microfluidic device; 138-control system. W, L the size. N+, N-, P denote doping type and doping level. x, y, z denote coordinates.

Detailed Description

Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. It is to be understood that the scope of the present invention is not limited to the disclosed embodiments, and that modifications and variations of the exemplary embodiments may be made by those skilled in the art in light of the present disclosure without undue effort and are intended to be included within the scope of the appended claims.

Fig. 1A schematically illustrates a partial cross-sectional view of an optical tweezer device according to an embodiment of the present invention. The optical tweezers device comprises a first electrode 124 of glass 128 coated with an Indium Tin Oxide (ITO) conductive coating 114 and a second electrode 116 electrically connected to the first electrode 124, between which an alternating current AC is applied. The alternating current AC may be square, sinusoidal or triangular. The first electrode 124 may also be other suitable ITO glass substitutes known in the art, such as AZO or GZO glass. The second electrode 116 is a metal electrode in this embodiment. Suitable metal electrodes include noble metals such as gold, silver, platinum, palladium, iridium, and the like; metals such as copper, tin, antimony, iron, cobalt, nickel, chromium, titanium, and manganese; or alloys such as platinum barium, palladium barium, iridium tungsten rhenium, iridium barium osmium, and the like. In this embodiment, the second electrode 116 is a gold electrode.

Above the second electrode 116, an array transistor structure is provided, which is electrically connected to the second electrode 116. A microfluidic channel 122 is provided between the upper surface of the transistor array and the lower surface of the conductive coating 114 of the first electrode 124. Microfluidic channel 122 is typically formed from a plurality of serially or parallel microchannels, each comprising a plurality of addressable microwells in which cells or other micro-objects can be located. The microfluidic channel 122 includes a fluid inlet and outlet (not shown) to be in fluid communication with the outside, and a microfluidic (e.g., cell culture fluid or physiological fluid) including cells 118 (illustrated as

cells

118a, 118b, 118c, and 118d, e.g., antibody-secreting hybridoma cells) flows into the microfluidic channel 122 via the inlet, flows through the microfluidic channel 122 in the direction indicated by arrow a to undergo processing and manipulation (including photoelectric detection, culture, screening, movement, etc.), and finally flows out of the outlet, thereby implementing an operation procedure of the microfluidic chip. The microfluidic channel 122 is typically made of a polymeric material, such as PMMA, PC, PS, PP, PE, PDMS, or the like, or by a photo-curing agent. The height of the microfluidic channel 122 is typically in the order of micrometers, for example 20 to 50 micrometers.

The array transistor structure includes a plurality of transistors 126 arranged in an array. The first insulating element 120 physically separates the individual transistors 126, thereby achieving electrical isolation between the individual transistors 126. Three transistors 126 are shown physically separated by two identical first

insulating elements

120a, 120 b. Each first insulating

element

120a, 120b is formed from an insulating

cap

112a, 112b and an insulating

barrier

148a, 148b (e.g., each of SiO ₂ Made of material). Insulating

caps

112a and 112b are located on the surface of transistor 126 and insulating

barriers

148a and 148b extend from insulating

caps

112a and 112b, respectively, down to substrate layer 110 of transistor 126. Each transistor 126 may be a phototransistor 126.

The array of transistors 126 may be regular or irregular, but is preferably regular, e.g., each transistor 126 is equally spaced in a square or rectangular parallelepiped form. When the array of transistors 126 is a regular arrangement of transistors 126, adjacent transistors 126 are spaced apart by a distance L, also referred to as the pixel period, which is the distance between the longitudinal center axes of adjacent insulating

barriers

148a and 148b. In this embodiment, L is about 5 to about 20 microns. The insulating barrier 148 has a longitudinal depth greater than the sum of the thickness of the emitter region 105, the thickness of the base region 106, and the thickness of the collector region of the transistor 126, for example, about 10% to about 30% of the sum of the thicknesses. For example, the insulating barrier 148 may have a longitudinal depth of about 2 to about 10 microns. The width of the insulating barrier 148 may be about 100 nm to about 2,000 nm. The portion of transistor 126 not covered by insulating cover 112 is referred to as a window, which has a size of about 1 to about 20 microns. As described below, in the present invention, the window is uniformly or non-uniformly divided into a corresponding number of sub-windows by the sub-emission regions.

Transistor 126 includes a substrate layer 110, a collector region 108 disposed on the substrate layer, a base region 106 disposed on collector region 108, and an emitter region 105 disposed on base region 106. The substrate layer 110 is located at the bottom of the transistor 126, which is directly electrically connected to the second electrode 116. The substrate layer 110 in this embodiment comprises an N-type dopant. The substrate layer 110 may be a heavily doped region. For example, the substrate layer 110 has a doping concentration of about 10 ¹⁸ cm ^-3 To about 10 ²¹ cm ^-3 . The thickness of the substrate layer 110 may be a suitable thickness as generally recognized in the art. For example, the thickness of the substrate layer 110 is typically greater than 50 microns, for example, a substrate layer 110 of about 50 to about 500 microns may have a resistivity of about 0.001 to about 0.05 ohm-cm.

Collector region 108 extends laterally to insulating barrier 148 and abuts adjacent insulating

barriers

148a and 148b at both ends, respectively. The collector region 108 is disposed on a side of the substrate layer 110 opposite the second electrode 116. Collector region 108 may have an N-type doping. Collector region 108 may be a lightly doped region relative to substrate layer 110. For example, collector region 108 has a doping concentration of about 10 ¹⁵ cm ^-3 To about 10 ¹⁸ cm ^-3 . The thickness of the collector region 108 may be about 100 nm to about 15,000nm, for example about 500 nm to about 3,000 nm.

It should be noted that the terms "heavily doped region" and "lightly doped region" and their corresponding notations are used in the present invention only in their relative sense, i.e., when one doped region has a higher doping concentration than another doped region, the higher doping concentration region is referred to as a heavily doped region and the lower doping concentration region is referred to as a lightly doped region, without necessarily being tied to the absolute value of its actual doping concentration. The N-type dopant may be any source of electrons. Examples of suitable N or n+ dopants include phosphorus, arsenic, antimony, and the like. The P-type dopant may be any source of holes. Examples of suitable P or p+ dopants include boron, aluminum, beryllium, zinc, cadmium, indium, and the like.

Base region 106 is disposed on the opposite side of collector region 108 from substrate layer 110, and in this embodiment, base region 106 contains a P-type dopant. A suitable doping concentration may be about 10 ¹⁶ cm ^-3 To about 10 ¹⁸ cm ^-3 . The base region 106 has a suitable thickness, for example, about 100 nm to about 3,000 nm.

The emitter region 105 is disposed on the opposite side of the base region 106 from the collector region. The upper surface of emitter region 105 forms the upper surface of transistor 126 and is exposed to microfluidic channel 122 opposite ITO conductive coating 114 of first electrode 124. The lower surface of the substrate layer 110 constitutes the lower surface of the transistor 126 and is electrically connected to the second electrode 116. When a patterned beam impinges on transistor 126, the beam penetrates emitter region 105 to base region 106, producing a photoelectric effect that turns on transistor 126.

In this embodiment, the emitter region 105 includes a first doped region 102 and a second doped region 104, wherein the second doped region 104 is adjacent to the base region 106, the first doped region 102 is disposed over the second doped region 104, and at least a portion of the first doped region 102 directly faces the ITO conductive coating 114 of the first electrode 124. The insulating cap layer 112 at least partially covers the first doped region 102. The first doped region 102 and the second doped region 104 each extend laterally and parallel to adjacent insulating

barriers

148a and 148b. The first doped region 102 and the second doped region 104 have the same doping type, and the first doped region 102 has a greater doping concentration than the second doped region 104. For example, the first doped region 102 and the second doped region 104 each comprise an N-type dopant, the first doped region 102 being a heavily doped region n+ and the second doped region 104 being a lightly doped region N-. When both the first doped region 102 and the second doped region 104 contain P-type dopants, the first doped region 102 is a heavily doped region p+ and the second doped region 104 is a lightly doped region P-. The doping concentration of the first doped region 102 may be about 10 to about 10 of the doping concentration of the second doped region 104 ⁶ Multiple times. For example, the doping concentration of the first doped region 102 may be about 10 of the doping concentration of the second doped region 104 ² To about 10 ⁵ Multiple, or about 10 ³ Multiple times. For example, the doping concentration of the first doped region 102 may be about 10 ¹⁸ cm ^-3 To about 10 ²¹ cm ^-3 The doping concentration of the second doped region 104 may be about 10 ¹⁵ cm ^-3 To about 10 ¹⁸ cm ^-3 。

In this context, the terms lateral, longitudinal, vertical correspond to the y, z, and x directions, respectively, in the xyz coordinate system shown in reference to fig. 1. The terms transverse, longitudinal, vertical are used herein in their relative sense only and are used for convenience of description only, i.e. elements described as transverse may also be described as longitudinal or vertical, correspondingly elements described as longitudinal and vertical are described as transverse, and so on.

In this embodiment, the base region 106 includes a lateral portion 150 that extends laterally to and abuts adjacent insulating

barriers

148a and 148b. The base region 106 further includes

longitudinal portions

142, 144, 146 extending from the lateral portion 150. The

longitudinal portions

142, 144, 146 include a first longitudinal portion 142 that extends from a transverse portion 150 to the second insulating member 140. The second insulating element 140 and the first insulating element 120 may be made of the same or different electrically insulating materials, e.g. each of SiO ₂ Is prepared. The second insulating element 140 completely covers the first longitudinal portion 142 and at least partially covers the first doped region 102. The second insulating element 140 is exposed at the transistor 126 to the surface spacer emitter regions 105a and 105b of the microfluidic channel 122. The thickness of the first longitudinal portion 142 is substantially equal to the thickness of the emitter region 105, and may be, for example, about 500 nm to about 4,000 nm.

In this embodiment, the base region 106 further includes second

longitudinal portions

144 and 146, the second

longitudinal portions

144 and 146 extending from the lateral portions 150 along the insulating

barriers

148a and 148b of the first insulating element 120 to the first insulating

caps

112a and 112b, respectively. The second

longitudinal portions

144 and 146 are covered by the first insulating

covers

112a and 112b, respectively, and the first insulating

covers

112a and 112b also at least partially cover the first doped region 102. The second

longitudinal portions

144 and 146 abut the insulating

barriers

148a and 148b, respectively, in the longitudinal direction, thereby physically isolating the emitter region 105 from the insulating

barriers

148a and 148b. Thus, the emitter region 105 is physically separated by the first and second

longitudinal portions

142, 144 and 146 of the base region 106 into at least two sub-emitter regions, namely a first sub-emitter region 105a consisting of the first and second doped regions 102a, 104a and a first sub-emitter region 105b consisting of the first and second doped regions 102b, 104 b. Each sub-emitter 105a and 105b is surrounded by first and second

longitudinal portions

142, 144, 146 of the base region 106, only a portion of the first

doped regions

102a and 102b of the sub-emitter 105a and 105b being exposed to the microfluidic channel 122. The number and configuration of the sub-emitter regions may vary, as described below, and depends at least in part on the number and arrangement of the first and second longitudinal portions of the base region.

The first longitudinal portion 142 has a first width W1, the second longitudinal direction 144 has a second width W2, and the second longitudinal direction 146 has a third width W3. The first width W1, the second width W2, and the third width W3 have the same or different values. In this embodiment, the second width W2 and the third width W3 may be substantially equal. For example, the ratio of the second width W2 to the third width W3 is about 1:10 to about 10:1, or about 1:5 to about 5:1, or about 1:3 to 3:1, or about 1:1.5 to 1.5:1, or about 1:1.2 to about 1.2:1, or about 1:1. The first width W1 may be less than or equal to the second width W2 or the third width W3. For example, the ratio of the first width W1 to the second or third width W2 or W3 is about 1:1 to about 1:10, or about 1:1 to about 1:8, or about 1:1 to about 1:6, or about 1:1 to about 1:4, or about 1:1 to about 1:3, or about 1:1.

For example, the first width W1, the second width W2, and the third width W3 are independently about 100 nm to about 1,000 nm, such as about 100 nm to about 800 nm, or about 100 nm to about 600 nm, or about 100 nm to about 400 nm, or about 100 nm to about 200 nm, or about 200 nm to about 1,000 nm, or about 200 nm to about 800 nm, or about 200 nm to about 600 nm, or about 200 nm to about 400 nm, or about 400 nm to about 1,000 nm, or about 400 nm to about 800 nm, or about 400 nm to about 600 nm, or about 600 nm to about 1,000 nm, or about 600 nm to about 800 nm, or about 800 nm to about 1,000 nm.

Referring to fig. 1B, a partial top view of the optical tweezer device of fig. 1A is shown (with the first electrode 124 removed for clarity). The dashed lines show the base region 106 covered by the first insulating cover layer 112 and the second insulating element 140, of which only the base regions of two are shown for the sake of brevity. As shown, the base region 106 includes two first

longitudinal portions

142a and 142b perpendicular to each other in the lateral direction and the vertical direction and intersecting each other, and second

longitudinal portions

144 and 146. The first and second longitudinal portions together physically separate the emitter region into four sub-emitter regions, shown as first

doped regions

102a, 102b, 120c, and 102d, respectively. In this embodiment, the first

longitudinal portions

142a and 142b have equal widths W1. In other embodiments, the first

longitudinal portions

142a and 142b may have unequal widths.

Fig. 1C shows a partial cross-sectional view of an array of phototransistors consisting of phototransistors 126 of the structure shown in fig. 1A. Fig. 1D shows a schematic diagram of a portion of a microfluidic device 136 comprising an optical tweezer device formed from phototransistor 126 of the structure shown in fig. 1A. The microfluidic device 136 includes an optical tweezer apparatus and a control system 138. The control system 138 generally includes a computer system 134, an image acquisition device 132 and a light pattern generating device 130 communicatively coupled to the computer system 134. The image acquisition device 132 is used to acquire images of the microfluidic channels and/or microwells, such as a camera with a CCD chip. The light pattern generating device 130 is used to generate a patterned light beam to excite the transistor. The intensity of the beam may be about 0.1W/cm ² To about 1000W/cm ² . The computer system 134 is communicatively coupled to the optical tweezers devices and controls interactions among the image acquisition device 132, the optical pattern generation device 130, and the optical tweezers devices according to preset instructions to perform microfluidic operations.

This embodiment extends one or more

longitudinal portions

142, 144, 146 from a lateral portion 150 of the base region 106, physically isolating the emitter region 105 into a plurality of sub-emitter regions 105a, 105b that share the base region 106 and the collector region 108. On the one hand, the

longitudinal portions

142, 144, 146 extend from the transverse portion 150 to the insulating

cover

112, 140 and thus closer to the light beam, illuminated by the light intensityThe base region 106 of this embodiment is larger and can receive more photons at the same illumination intensity than a base region without the longitudinal portion. On the other hand, the material constituting the insulating covers 112 and 140 (for example, siO ₂ ) Is better than the material of the emitter region 105 (e.g., crystalline silicon) overlying the base region 106, and the

longitudinal portions

142, 144, 146 of the base region 106 are therefore able to receive more photons. Therefore, the transistor structure realizes larger photo-generated current without changing the light intensity of the irradiation light beam or the window size of the transistor, thereby generating larger DEP force and facilitating the manipulation of micro-objects in the micro-fluid channel. In addition, the presence of multiple sub-emissive regions results in a denser, more uniform distribution of the non-uniform electric field generated by the illumination relative to the undivided emissive regions, thereby facilitating manipulation of the micro-object.

Fig. 2A shows a partial cross-sectional view of a transistor array in an optical tweezer device according to another embodiment of the present invention. Fig. 2B shows a partial top view of the transistor array, with only the base region 206 of one of the windows shown in dashed lines for simplicity. The illustrated transistor array is similar to the embodiment shown in fig. 1, except that the number of first longitudinal portions of the base region 206 is greater. In the illustrated embodiment, the number of first longitudinal portions is 4, first

longitudinal portions

242a, 242b, 242c and 242d, respectively, wherein the first

longitudinal portions

242a, 242b are parallel in the same direction and perpendicularly intersect the parallel first

longitudinal portions

242c, 242d. The first

longitudinal portions

242a, 242b, 242c and 242d, together with the second

longitudinal portions

248a, 248b, 248c and 248d, together physically separate the emitter region 205 into nine sub-emitter regions, shown as first doped regions 102 a-102 h, respectively. The widths of the four first longitudinal portions W1a, W1b, W1c and W1d, respectively, may be equal or unequal. The widths W1a, W1b, W1c, and W1d are each independently from about 100 nm to about 1,000 nm. The widths W2, W3, W4, W5 of the second longitudinal portions are independently from about 100 nm to about 1,000 nm, and their ratio relationships are described with reference to the relationships of W2 and W3 as before. The ratio relationships of W1a to W1d to W2 or W3 or W4 or W5 are as described above with reference to the relationships of W1 to W2 or W3.

It is envisioned that the number and direction of the first longitudinal portions may vary. For example, the first longitudinal portions may be two, three, four or more, they may be co-directional or non-directional, and may be angled, parallel or perpendicular. For example, the first longitudinal portion may be two equidirectional parallel longitudinal portions, thus separating the emission area into three sub-emission areas together with the second longitudinal portion. The three sub-emissive regions may be of equal volume. And, the three sub-emission regions may be rectangular parallelepiped. For another example, the first longitudinal portion is three in number, two of which are parallel in the same direction and the other perpendicularly intersects them, thereby separating the emission area into six sub-emission areas together with the second longitudinal portion. The six sub-emissive regions may be of equal volume. And, the six sub-emission regions may be cubes. It is also contemplated by those skilled in the art that the plurality of first longitudinal portions may be arranged in an angular fashion to obtain an emitter region of non-rectangular cross-section. It is also contemplated by those skilled in the art that the number of sub-emissive areas may be odd.

Fig. 3 shows a partial cross-sectional view of a transistor array in an optical tweezer device according to another embodiment of the present invention. The illustrated transistor array is similar to the embodiment shown in fig. 1, except that the base region 306 includes a lateral portion 350 and a first longitudinal portion 342, but does not include at least one second longitudinal portion extending along the insulating barrier 348 to the insulating cap layer 312. In this embodiment, a lateral portion 350 of the base region 306 extends laterally and abuts along the insulating barriers 348a, 348b. One end of at least one of the sub-emissive regions abuts an insulating barrier 348. Thus, the first longitudinal portion 342 of the base region 306, together with the first insulating element 320, physically isolates the emitter region 305 into at least two sub-emitter regions 305a and 305b. As previously described, each sub-emitter may be comprised of a first

doped region

302a or 302b and a second doped region 304a or 304 b. Thus, at least one sub-emitter is physically separated by the lateral portion 350 of the base region 306, the first longitudinal portion 342, and the insulating barrier 348 of the first insulating element 320, with only a portion of the

first emitter regions

302a, 302b exposed to the microfluidic channel.

It is contemplated that the base region 306 may not include any second longitudinal portion, i.e., in either direction, a longitudinal portion extending along the insulating barrier 348 to the insulating cap 312, or that the base region 306 may include a second longitudinal portion in one or more directions such that at least one sub-emitter is physically separated by the lateral portion 350 of the base region 306, the first longitudinal portion 342, and the insulating barrier 348 of the first insulating element 320, and at least one sub-emitter is physically separated by the lateral portion 350, the first longitudinal portion 342, and the second longitudinal portion of the base region 306. It is also contemplated that the number, direction, and arrangement of the first longitudinal portions 342 may be varied as previously described to vary the number, volume, and arrangement of the sub-emissive areas.

Fig. 4 shows a partial cross-sectional view of a transistor array in an optical tweezer device according to another embodiment of the invention. The illustrated transistor array is similar to the embodiment shown in fig. 3, except that the number of first longitudinal portions of the base region 406 is greater. In the illustrated embodiment, the number of first longitudinal portions is 2, 442a, 442b, respectively. The first longitudinal portions 442a, 442b extend in parallel and perpendicular directions to the insulating barrier 448. The first longitudinal portions 442a, 442b, together with the first insulating elements 420a, 420b and the lateral portion 350 of the base region 406, physically separate the emitter region 405 into three sub-emitter regions 405a, 405b and 405c. In this embodiment, at least one sub-emitter 405b is physically separated by a lateral portion 450 and a first longitudinal portion 442a, 442b of the base region 406, and at least two sub-emitters 405a, 405c are physically separated by a lateral portion 450, a first longitudinal portion 442a or 442b, and a first insulating element 420a or 420b of the base region 406. It is contemplated that the number, direction, and arrangement of the first longitudinal portions 442 may be varied as previously described to vary the number, volume, and arrangement of the sub-emissive areas.

The transistor, optical tweezer device and microfluidic device provided by the invention can be prepared by conventional technology in the field. Those skilled in the art will be able to fabricate the transistor of the present invention without undue explanation based on the level of existing semiconductor fabrication processes, in conjunction with the illustration and description herein. By way of example only, fig. 5 schematically illustrates a method 500 of fabricating a phototransistor of the present invention.

The method 500 includes a step 502 of providing a semiconductor substrate (e.g., silicon) including a doped substrate layer for forming a substrate layer in embodiments of the present invention and an undoped layer disposed thereon for forming a collector region, a base region, and an emitter region in embodiments of the present invention.

In step 504, a collector doped layer is formed in close proximity to the doped substrate layer in the undoped layer, the collector doped layer forming a collector region in embodiments of the present invention, the collector doped layer and the doped substrate layer may be of the same doping type (e.g., both N-type doping) but may have different doping concentrations. For example, the collector doped layer is a lightly doped layer and the doped substrate layer is a heavily doped layer. The semiconductor material obtained after step 504 comprises a doped substrate layer and a collector doped layer.

Step 506 forms a trench in the resulting semiconductor material and fills the trench with an electrically insulating material (e.g., siO ₂ ). The trench extends through the collector doped layer and into the doped substrate layer, thereby forming an insulating barrier in embodiments of the invention.

Further, in step 508, a base doped layer is formed in the collector doped layer by ion implantation, the base doped layer having a different doping type (e.g., P-type doping) than the collector doped layer and the doped substrate layer. The thickness of the base doped layer and the collector doped layer can be controlled by controlling parameters such as the time, the speed, the implantation amount and the like of ion implantation so as to meet the requirements of the invention on the thickness of the base doped layer and the collector doped layer.

In step 510, a plurality of sub-emitter doped layers are formed in the base doped layer by ion implantation, the emitter doped layer having a different doping type (e.g., N-type doping) than the base doped layer. The emitter doped layer may be formed by separate ion implantation steps to form a first doped layer and a second doped layer having different doping concentrations, e.g., the first doped layer has a higher doping concentration than the second doped layer to form the first doped region and the second doped region of the emitter region in embodiments of the present invention. Similarly, by controlling parameters such as the time, the speed, the implantation amount and the like of the ion implantation, the thicknesses of the formed first doping layer, the second doping layer and the base doping layer can be controlled so as to meet the requirements of the invention on the thicknesses of the layers.

It is noted that while the doping type and doping level are shown in the figures, it is well known to those skilled in the art that the illustrated NPN transistor may be replaced by a PNP transistor structure without affecting the achievement of the objectives of the various embodiments of the present invention.

The foregoing is a representative example of embodiments of the present invention and is provided for illustrative purposes only. The present invention contemplates that one or more features used in one embodiment can be added to another embodiment to form an improved or alternative embodiment without departing from the purpose of the embodiment. Likewise, one or more features used in one embodiment may be omitted or substituted without departing from the purpose of the embodiment to form a substituted or simplified embodiment. Furthermore, one or more features used in one embodiment may be combined with one or more features of another embodiment to form improved or alternative embodiments without departing from the purpose of the embodiments. The present invention is intended to include all such improved, alternative, and simplified embodiments.

Claims

1. A transistor optical tweezer, comprising:

a first electrode;

a second electrode electrically connectable to the first electrode;

a phototransistor array disposed between the first electrode and the second electrode, the phototransistor array being comprised of phototransistors distributed in an array, each phototransistor being physically separated from each other by a first insulating element, each phototransistor including a collector region, a base region, and an emitter region supported by a substrate;

a microfluidic channel disposed between the first electrode and the array of phototransistors, characterized in that,

for each phototransistor, its emitter region includes at least two sub-emitter regions that are physically separated from each other at least in part by the base region, and the at least two sub-emitter regions have a common base region and collector region.

2. The transistor optical tweezers of claim 1, wherein the base region comprises a lateral portion and a longitudinal portion extending from the lateral portion, the lateral portion extending to the first insulating element, the longitudinal portion comprising a first longitudinal portion extending from the lateral portion of the base region to the second insulating element and physically isolating the sub-emitter at least in part.

3. The transistor optical tweezer of claim 2, characterized in that at least one sub-emitter is physically separated by a lateral portion of the base region, a first longitudinal portion of the base region and the first insulating element.

4. The transistor optical tweezer of claim 2, wherein the longitudinal portion comprises a second longitudinal portion abutting and extending along at least one of the first insulating elements, the second longitudinal portion being spaced apart from the first longitudinal portion.

5. The transistor optical tweezers of claim 4, wherein at least one sub-emitter is physically separated by a lateral portion of the base region, a first longitudinal portion of the base region, and a second longitudinal portion of the base region.

6. The transistor optical tweezers of claim 2, wherein the first longitudinal portion comprises a plurality of first longitudinal portions parallel and/or perpendicular to each other.

7. The transistor optical tweezers of claim 6, wherein at least one sub-emitter is physically isolated by only a lateral portion of the base region and a first longitudinal portion of the base region.

8. The transistor optical tweezer of claim 1, characterized in that each sub-emitter is surrounded by a base region but at least partially exposed to the microfluidic channel.

9. The transistor optical tweezer of claim 4, wherein the first longitudinal portion has a first width and the second longitudinal portion has a second width, the first width and the second width independently being about 100 nm to about 1,000 nm.

10. The transistor optical tweezer of claim 6, wherein the width of each of the first longitudinal portions is independently from about 100 nm to about 1,000 nm.

11. The transistor optical tweezer according to any of claims 1 to 10, characterized in that each sub-emitter comprises a first doped region and a second doped region, the doping concentration of the first doped region being higher than the doping concentration of the second doped region.

12. The transistor optical tweezer of claim 11, wherein the first doped region has a doping concentration of about 10 ¹⁸ cm ^-3 To about 10 ²¹ cm ^-3 The second doped region has a doping concentration of about 10 ¹⁵ cm ^-3 To about 10 ¹⁸ cm ^-3 。

13. The transistor optical tweezers of any one of claims 1 to 10, wherein the emitter region of each phototransistor comprises three, four, six, eight or nine sub-emitter regions.

14. The transistor optical tweezer according to any of claims 1 to 10, characterized in that each sub-emitter has a substantially equal volume.

15. The transistor optical tweezer according to any of claims 1 to 10, characterized in that the collector region of each phototransistor extends transversely to the first insulating element and has no longitudinal extension.

16. The transistor optical tweezer of claim 1, wherein each phototransistor is spaced apart at a pitch of about 5 microns to about 20 microns.

17. The transistor optical tweezer of claim 1, wherein the microfluidic channel comprises a conductive medium having cells.

18. A microfluidic device comprising the transistor optical tweezers of any one of claims 1 to 17.